1. Field of the Invention
This invention relates to an air attachment for a cutter platform of a harvester which may be used for harvesting grain and various other crops.
2. Description of the Prior Art
In the specification of the U.S. Pat. No. 4,406,112 lodged originally in the name of Donald George Brooks but assigned to the Applicant herein, there is a disclosure of a pressure air manifold arrangement which is effective in dispensing with a beater reel for the harvester platform, and, in lieu thereof, in blowing the heads of a crop across the platform after the heads have been severed by the knife blades of the platform. This arrangement has been outstandingly successful, but modifications have been needed when different types of crops are to be harvested. For example, if wheat, lentils, oats, lucerne and sorghum are to be harvested, the requirement is for only a narrow depth of air curtain to blow the heads across a platform and into the space which is controlled by the auger to transport the cut crop to a central location on the harvester from which they are in turn transported to a thresher drum or similar. If however barley, sunflowers, mung bean, or millet is to be harvested, it is desirable that the curtain of air should have greater depth to ensure that any seeds released during the cutting or transporting are blown across to be moved into the feeder house by the auger, and it is therefore quite difficult to get the required air movements effective for these two types of harvesting, with the configuration of air nozzle outlets illustrated in said U.S. Pat. No. 4,406,112.
Still further, lupins, some bearded cereal crops, soy beans, edible beans and other legume crops (e.g. cow peas), and rape seed, and any requirement for taking long straw or high and low crop heads growing together, require an even wider curtain of air. In particular, lupins are difficult to harvest efficiently because of the release of seeds by shattering, sometimes occurring merely with the heat of the sun, and often occurring when the lupins are subject to shock, when for example the stalks are cut by the knife blade of the harvester. The bushes which are released when the stalks of lupins are cut are so light and bunchy that they are difficult to transport transversely by the header platform auger.
Another problem which is frequently encountered is that the auger tends to build up a heavy crop at the feeder house location where it is required to be transported rearwardly in the machine to a thresher drum. This requires still further assistance particularly when a beater reel is dispensed with, as with air harvesting equipment.
Apart from the applicant's own Australian Patent No. 534,795 (U.S. Pat. No. 4,406,112), the most relevant prior art known to the Applicant comprises PHILLIPS U.S. Pat. No. 2,670,586, ALTGELT U.S. Pat. No. 1,900,269; MILLER U.S. Pat. No. 3,193,995; OSTEEN U.S. Pat. No. 3,165,874; and Italian Patent No. 624,215 COMOGLIO. In all this prior art, the air curtain depth was limited to a small dimension, which, according to experiments conducted by the Applicant herein, is unlikely to exceed 50 mm at a distance of 600 mm from the nozzles.